Gas stream shielded arc welding devices are commonly used for all types of welding tasks. A metallic wire providing the welding flux is fed from the machine through a nozzle. An electrical circuit is comprised of the wire and the workpiece to be welded, and as the wire contacts the workpiece, the circuit is completed. Consequently, as electrical current travels across the gap between the wire and the workpiece, the arc heats the wire to a melting point. The wire is controlled by the welder through the use of a hand-held welding nozzle. This nozzle also directs the flow of a shielding fluid such as an inert or protective gas from the welding machine. Various fluids can also be used for shielding purposes, but hereinafter, all shielding fluids will be discussed in the context of a gas. This gas serves to shield the molten metal from oxidation until the weld cools and hardens, and also may help lessen any explosion hazard by protecting the hot weld area from outside gases. This method and apparatus for gas stream shielded arc welding is well known in the art, as shown, for example, in U.S. Pat. No. 2,870,320, issued to H. H. Mathews on Jan. 20, 1959.
The welding nozzle is the subject of interest in the present invention. A welding nozzle is normally replaced fairly frequently because of wear, and as such is considered reasonably disposable. The welding nozzles are normally made of metallic materials, but this is not a requirement. There also exist various styles of nozzles for differing welding applications.
Since shielding gas coverage directly impacts the manufacture of a quality weld, the directing of this gas is also quite important. Because the gas flows under pressure, the gas is constantly displacing outside air from the weld area. The displacement of outside air provides for the weld to harden and cool in an inert atmosphere to produce a strong and lasting weld.
There exist many different styles of welding nozzles which aim to maximize the coverage of the shielding gas while using a limited amount of the gas in order to keep the welding process cost-effective. Reference is made to a style of welding nozzle disclosed in U.S. Pat. No. 3,495,066 issued Feb. 10, 1970 to Y. Broyard et al, in which the shielding gas is simply forced through the bore of the welding nozzle and thus onto the weld area. The main disadvantage of this method is that the gas tends to blow away from the weld area very quickly, thus requiring a large volume of gas to adequately shield the weld area from oxidation.
Another common welding nozzle design is disclosed in the '320 patent, which uses separate passageways to direct the shielding gas through angled (in this case, right-angled) orifices in the end portion of the welding nozzle to induce a swirling aspect to the shielding gas as it exits from the welding nozzle. The vortex thus formed prevents the gas shield near the weld area from dissipating as quickly as a non-swirling shield, but leaves the center of the vortex relatively calm and may provide an opportunity for outside air to contaminate the weld area.
The present invention is directed to overcoming one or more of the problems as set forth above.